This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Brain injury from explosive blast is a prominent feature of contemporary combat. We will use sophisticated measures of brain function and structure to characterize brain injury from explosive blasts in a sample of Operation Iraqi Freedom (OIF) National Guard soldiers who returned from deployment in the fall of 2007. Biological measures that directly assess neural disruption will be used to characterize differences in brain structure and function between blast-related brain injury and post-traumatic psychopathology. To fully characterize the effects of blast on the brain and differentiate them from post-traumatic stress disorder, we will contrast groups of soldiers exposed to blast with groups experiencing post-traumatic stress disorder. It is expected that this DoD-funded study may take up to four years. This study will provide a means for separating co-occurring conditions of brain injury and psychological distress due to explosive blast and post-traumatic psychopathology. The results of this research will help clinicians better differentiate between post-traumatic stress disorder and brain injury due to explosive blast by increasing our understanding of the essential features of the conditions in terms of neural function and structure. Better differentiation between the two conditions will allow clinicians to design more appropriate treatment protocols. Results of this research will be used to inform diagnosis and characterize mechanisms of recovery after blast-related neural injury to allow the creation of interventions that return soldiers to maximum levels of functioning.